John King Chains

Chain and Sprocket Fault Finding

There can be many reasons why chain and sprocket installations of any type can give difficulties in service and we can only list a small number of suggestions when operating problems occur.

FAULT

CAUSE

REMEDY

Fractured Chain Bush / Barrel

Chain Speed too High

Chain of Shorter Pitch but equivalent strength

     
 

Heavy Shock Loads

Investigate to reduce shock Loads

     
 

Corrosion Pitting

Consider using special material or Improve Lubrication

 

Roller Flatting due to Skidding

Too lightly loaded System

Increase load within limit of chain

 

Heavy Load where Friction between bush and roller bore overcomes lever friction effect of friction at roller periphery

Increase chain size if no reduction possible

 

Excessive lubricant on chain track

Clean tracking

 

Canting Over of chain on Track

Investigate

Tight Chain Joints

Material packed in chain

Clean & re- lube

 

Frozen / Seized Chain

Clean & re- lube

 

Incorrect Lubricant

Clean & re- lube

 

Corrosion

Investigate

 

Mal-alignment

Check structure

 

Fractured Chain Plates
Fractured Bearing Pin
Elongated Linkplate Holes

Overload above maximum Chain working capacity

Investigate for foreign object causing construction.

Check alignment between drive & tail sprockets

   

Protect with chain Overload Device

   

Check Power Consumption

 

Loose or Damaged Chain Attachments / Brackets

High Unit Shock Loads

Investigate

 

Incorrect Assembly of
Slats / Carrier Assemblies

Re-align to ensure correct phasing

 

Twisted Chain causing Flexing and Cross Chain Loads

Check for inaccuracies on assembly

 

Excessive Roller Bore Wear

High Unit Load

Distribute Load

 

Twisted Slats / Carriers

Investigate, highlight, correct

 

Unsatisfactory Lubrication

Improve Lubrication

 

Excessive Noise

Mis-alignment of Chain Tracking

Check all Structure Alignments

 

Too little or too much Chain Slack

Re-tension chain

 

High Speed

Use Shorter Chain Pitch Size

 

Chain Sprocket Wheels Worn

Replace

 

In-effective Lubrication Damaged / Incorrectly positioned chain tracking

Lubricate correctly Investigate and adjust as necessary

Uneven Running

“Stick Slip” / Hunting

See Roller Flatting. Check Drive for adequate capacity

 

Polygonal Action of closely spaced sprockets in a complex circuit

Increase sprocket chainwheel centres or reposition wheels

 

High Friction at Idler Sprockets

Lubricate or fit low friction bearings

 

Polygonal Action at Drive Chainwheel

Use larger diameter sprocket

 

Chain Whip

Excessive Slack

Adjust correctly

 

Worn Tooth Form

Replace Chainwheel

 

Long unsupported chain strands

Fully guide return chain strand

 

Chain Clings to Sprocket Teeth

Incorrect Tooth Form

Replace

 

Worn Tooth Form

Replace

 

Heavy Tacky Lubricant

Clean & re-lube

 

Stiff Chain Joints

See chain assembly Procedures

 

Chain Climbs Sprocket Teeth

Excessive Tooth Form Wear

Replace

 

Build Up of Excessive Chain Slack

Adjust Chain

 

Chain Elongation

Replace Chain

 

Severe Overloads

Investigate, highlight, correct

Material Packing between Chain and Tooth Root

Remove obstruction

Consider change to sprocket profile design


20.1 General Inspection Procedures
1. Place spirit level on all shafts for accuracy of horizontal settings.
2. Check visually for squareness.
3. Rotate shafts through 90 degrees and inspect again.
4. Release any chain tension weights or remove tension loads. Disconnect chain from head shaft sprockets. Place bar across chain sprocket tooth root and check alignment using a spirit level to sight against the shaft.
5. Use diagonal cross wires to ensure squareness of twin chain strand sprockets.
6. Record any rubbing marks made by the inside face of the chain side link plates on the sprocket tooth flanks. This indicates position and severity of misalignment.
7. In twin strand chain systems, ensure that one tail shaft sprocket is free running to prevent chain “wind up”.